JP6460359B2 - Creating 3D objects - Google Patents

Description

  As a potentially convenient method for generating a three-dimensional object, an additive manufacturing system that generates a three-dimensional object for each layer has been proposed.

  Some additive manufacturing systems operate by selective processing of building materials. In order to form individual layers or slices of the three-dimensional object to be created, a suitable layer of building material is deposited in the production region and the selected region corresponding to one slice of the three-dimensional object to be created The build material is treated to solidify the build material within. The rest of the build material remains unsolidified.

2 is an embodiment of a method according to the present disclosure. 2 is an embodiment of a method according to the present disclosure. 1 illustrates one embodiment of an optical sensor device. 1 illustrates one embodiment of an additive manufacturing system according to the present disclosure. Fig. 4 shows an example of different cross-sectional profiles of one layer of building material. 3 shows another embodiment of a method for creating a three-dimensional object. 6 is a flow chart illustrating one embodiment of an iterative process for improving edge sharpness.

  Here, some embodiments will be described as non-limiting examples with reference to the drawings.

  An additive manufacturing system has been proposed to create a three-dimensional object. The additive manufacturing system creates an object for each layer. A conceptual model (eg, a computational model) of the object being created can be divided into a series of slices across the object. Each such slice is then generated sequentially and subsequent slices are formed on the preceding slice to form the overall object.

  Depending on the additive manufacturing system, each layer is formed by selective processing of the construction material. One layer of a suitable build material can be deposited in the build region. The building material is then processed to solidify the building material in the selected region corresponding to one slice or piece of the object being created, and the building material in the region not corresponding to the object being created is non-solidified. Will remain. Thus, this treated layer (also referred to herein as a build layer) can include areas of solidified build material and areas of non-solidified build material. Depending on the object or objects being created, there may be one region of solidified building material in a given building layer, or multiple separate regions of solidified building material. And each of the plurality of discrete regions can be surrounded by a region of the non-solidified building material, or the region of solidified building material can be When extending to the edge, it can be at least partially surrounded by a region of the building material that has not solidified. The most recent building layer becomes the top layer of the building region and is formed on top of the previous building layer, where the solidified region of the building material of one building layer is fused with the solidified region of the previous building layer, It will be understood.

  In some embodiments, the processing of the building material to form the building layer selectively supplies a drug to at least a portion of the surface of the building material layer and temporarily applies a predetermined level of energy to the layer of building material. Can be applied to. In some embodiments, the supplied drug can be a coalescing agent. The coalescing agent can be selectively delivered, for example, to a region of the building material corresponding to a slice of the object being created. In some embodiments, the applied drug can be a coalescence modifier. In some embodiments, both coalescing agents and coalescence modifiers can be selectively supplied.

  The temporary application of energy can cause the parts of the building material supplied or infiltrated with the coalescing agent to coalesce by heating beyond the melting point of the building material. This temperature is referred to herein as the melting temperature. Upon cooling, the merged part becomes solid and forms part of the generated three-dimensional object.

  The coalescence modifier can be used for various purposes. In one embodiment, a coalescence modifier can be used that serves to reduce the degree of coalescence of the building material to which it has been applied and / or penetrated. Such coalescence modifiers can be considered as coalescence inhibitors, for example adjacent to the area where coalescence is supplied to help reduce the effects of lateral coalescence bleed. It is possible to supply to the area of building material to be. This can be used, for example, to improve the fineness or accuracy of an object's edge or surface and / or to reduce surface roughness. In another embodiment, the coalescence modifier can be supplied interspersed with the coalescence, which can be used to allow the properties of the object to be altered.

  In the embodiments described herein, the coalescing agent and / or coalescence modifying agent can include a fluid that can be delivered using any suitable fluid delivery mechanism (also referred to as a drug distributor). is there. In one embodiment, the drug is supplied in droplet form. The coalescing agent can be a strong light absorber such as a pigment colorant. In some embodiments, the drug dispenser can be a print head. The drug dispenser can be placed, for example, on a suitable scanning stage.

  According to one non-limiting embodiment, a suitable coalescing agent is an ink-type formulation comprising carbon black (such as the commercially available ink formulation known as CM997A available from Hewlett-Packard Company). ). In one embodiment, such an ink can further include an infrared light absorber. In one embodiment, such an ink can further include a near infrared light absorber. In one embodiment, such ink can further include a visible light absorber. Examples of inks that contain visible light enhancers include dye-based colored inks and pigment-based colored inks (eg, commercially known as CE039A and CE042A available from Hewlett-Packard Company) Etc.).

  In one embodiment, saline can be used as a coalescence modifier. In another embodiment, an ink commercially available from Hewlett-Packard Company, known as CM996A ink, can be used as a coalescence modifier. In another embodiment, it has also been demonstrated that an ink commercially available from Hewlett-Packard Company, known as CN673A ink, acts as a coalescence modifier.

  In the embodiments described herein, references to building materials can include building materials that are, for example, powder-based building materials. As used herein, the term “powder-based material” is intended to encompass dry and wet powder-based materials, particulate materials, and particulate materials. The build material can consist of a single material or can be a mixture of multiple constituent materials. In some embodiments, the build material is typically a weakly light absorbing polymer powder medium. In other embodiments, the build material is a thermoplastic.

  In the embodiment described herein, a three-dimensional object is constructed by stacking and fusing together portions of a plurality of layers of building material one after another. The layer of build material that has not solidified is deposited to form a flat surface (referred to herein as the build surface). This layer is processed, for example, as described in one of the embodiments described above to form a build layer having multiple regions of solidified build material. A layer of new build material can then be deposited on the previous build layer to form a new flat surface for forming the next build layer. This process can be repeated until the desired object is formed. In this way, the formed object is completed and supported by a building material that has not solidified during fabrication. When the object is properly cooled, it can be removed from the fabrication area and separated from the non-solidified building material.

  The characteristics of the object being created depend on a number of different factors. The original conceptual model of the object used and the number and size of the slices defined will obviously have an impact. Because of the actual fabrication process itself, the materials used (eg, building materials, coalescence agents, and coalescence modifiers) can vary in many settings of the production process (eg, the amount of drug used (eg, droplets). As well as density, droplet size, etc.) and applied energy (eg, amount or duration of heating)).

  One property of interest is surface roughness. The surface roughness of the fabricated object is determined, at least in part, by the transition between the solidified region of the building material and the non-solidified region of the building material in the building layer. For this reason, the profile of the transition between the edge of the slice of the created object (ie solidified area) and the non-solidified structural material can affect the quality of the finished object. It becomes. Inaccurate edges will lead to reduced accuracy of the fabricated parts.

  Therefore, the process settings of the additive manufacturing system can be set to provide specific edge accuracy for the material used. However, it will be appreciated that changes in ambient conditions, or changes in the manner in which the additive manufacturing system is actually operating, can lead to poor edge definition.

  For example, if ambient conditions change and excessive heat is applied during the treatment process, building materials that were not intended to be melted may be inadvertently fused. Ambient conditions mean, for example, that the amount of coalescence modifier used was insufficient, in which case the edges are not as sharp as intended and will affect the part quality. . In addition, misalignment of the drug distributor, or cross-contamination between coalescence modifier and coalescence may in some cases cause inaccurate edges.

  In an embodiment of the present disclosure, one edge profile is determined for one building layer. The edge contour can be determined by measuring the change in height of the build layer across the transition between the solidified and non-solidified build material regions. In some embodiments, process settings for forming subsequent build layers can be controlled based on the edge profile.

  As described above, creating a three-dimensional object with an additive manufacturing system involves depositing a layer of building material and processing the layer to solidify the region of the building material that has solidified and the region of the building material that has not solidified. Forming a build layer comprising: Forming the solidified region of the build material can include heating and coalescing the build material in the selected region and then cooling to solidify. As a result of the coalescence of the building material (which can be deposited in powder-based form) within the selected region, the thickness of the solidified building material is less than the thickness of the non-solidified building material in the building layer. Become. For example, the build material can be deposited to a first thickness prior to processing. After processing, any region of the building material that has solidified may have a second, thinner thickness. For example, a first thickness on the order of 100 μm may result in a second thickness on the order of 50 μm, depending on the material systems. However, the thickness of the non-solidified building material of the building layer can remain substantially equal to the first thickness (100 μm in this example).

  Thus, the height difference in the transition zone between the solidified construction material region and the non-solidified construction material region can provide information on the edge profile of the solidified region. Will be understood.

  FIG. 1 a illustrates one embodiment of a method 100 for creating an object according to the present disclosure. The method includes forming a building layer that includes a region of solidified building material and a region of non-solidified building material (block 101). Formation of the building layer can include depositing a layer of non-solidified building material and processing the building material to form a solidified region of building material. The construction layer can be formed by any of the above-described embodiments.

  The method further includes determining an edge profile of the building layer (block 102). Determining the edge profile can include measuring a change in height of the build layer across a transition between a region of solidified build material and a region of non-solidified build material. .

  According to one embodiment, the change in height can be measured using an optical sensor. In some embodiments, the optical sensor can include an optical focus error sensor.

  Optical focus error sensors are used in various applications, for example, as optical pickups such as CD or DVD read heads. Thus, such sensors can be easily obtained commercially at a relatively low cost.

  FIG. 2 shows an example of the optical focus error sensor 200. The light source 201 generates a beam of optical radiation that is directed to an element such as a beam splitter 202. The beam splitter 202 directs part of the optical radiation through the lens 204 to the surface 203 to be analyzed. Radiation reflected from the surface is directed to detector 205 via lens 204 and beam splitter 202. The detector 205 can determine the shape of the reflected beam incident on the detector, for example, a sensing quadrant 205a- disposed in a square grid as shown on the right side of FIG. A quadrant light detector with 205d can be provided. The detector can be connected to a readout circuit 206. The readout circuit 206 can determine a focus error signal. In some embodiments, the focus error signal is obtained by summing the photocurrents from the diagonally opposite quadrants, i.e., summing the photocurrents from quadrants 205a, 205d, and the photocurrents from quadrants 205b, 205c. It is determined by summing and finding the difference between them. Therefore, the value FE corresponding to the focus error is obtained by the following equation.

FE = (I _a + I _d ) − (I _b + I _c ) Equation (1)
Here, I _a photocurrent from the quadrant 205a, the I _b photocurrent, I _c from quadrant 205b photocurrent from quadrant 205c, the I _d is the photocurrent from the quadrant 205d.

  The sensor setting is such that the shape of the reflected beam received by the detector 205 is determined by the distance between the lens 204 and the reflecting surface 203. When the surface 203 is located at a characteristic length (eg, focal length), the shape of the beam incident on the detector 205 is circular. As shown in the upper right of FIG. 2, the circular shape 207a can illuminate all quadrants 205a-205d of the detector substantially equally. In this case, the value FE corresponding to the focus error is substantially equal to zero, that is, the total photocurrent from quadrants 205a and 205d is substantially equal to the total photocurrent from quadrants 205b and 205c.

  The sensor 200 is arranged at least within a certain range of the characteristic length so that the reflected beam begins to take an elongated or elliptical shape away from having a circular shape, and its degree of elongation and its The axis will be related to the degree of deviation from the characteristic length.

  The beam splitter 202 is such that when the distance between the lens 204 and the surface 203 increases from the characteristic length, i.e. when the surface 203 is further away, the size of the beam on the detector is first. Astigmatism is introduced into the optical path in such a way that it increases along the axis and decreases along the second orthogonal axis. In the middle right of FIG. 2 is shown a shape 207b that can occur when the surface 203 is further than the characteristic length from the sensor. In this case, the total photocurrent from quadrants 205a and 205d is less than the total photocurrent from quadrants 205b and 205c. For this reason, the value FE corresponding to the focus error is a negative value relating to how far the distance between the sensor 200 and the surface 203 is from the characteristic length.

  However, if the distance between the lens 204 and the surface 203 decreases from a characteristic length, i.e., the surface 203 is closer, the dimension of the beam on the detector is the first axis. And increase along the second orthogonal axis. The lower right of FIG. 2 shows a shape 207c that can occur when the surface is closer to the sensor than the characteristic length. In this case, the total or combined photocurrent from quadrants 205a and 205d is greater than the total or combined photocurrent from quadrants 205b and 205c. For this reason, the value FE corresponding to the focus error is positive with a value related to how far the distance between the sensor 200 and the surface 203 is away from the characteristic length.

  The relationship between the value FE corresponding to the focus error and the distance of the surface from the sensor 200 is substantially linear over a specific distance range. This linear range can be defined by the arrangement of the sensor components, but in one embodiment, the focus error value can be linear over a range on the order of about 5 μm (eg, a range of 6 μm). is there. Therefore, the optical sensor can determine the change in height with a spatial resolution lower than about 5 μm, that is, it can characterize any height difference with an accuracy exceeding about 5 μm.

  By scanning the optical sensor transversely to the surface of the building layer, the distance between the surface of the building layer and the sensor changes with the change in height, which is the detection of values related to the focus error. It leads to possible changes.

  As mentioned above, the operating range where the focus error is linearly related to distance may be smaller than the expected overall height change across the build layer. For example, in some systems, the expected change in height across the build layer from the solidified building material region to the non-solidified building material region may exceed the order of 50 μm.

  Accordingly, the optical sensor may include a translation stage 208 for translating the optical sensor or at least a portion of the optical sensor in the longitudinal direction. The translation stage can translate the lens 204 with respect to the beam splitter, for example. In some embodiments, the translation stage can include, for example, an inductor that provides a linear longitudinal translation of the lens 204, the range of translation depending on the current supplied to the inductor. By definition, a known amount of current will provide a known amount of displacement.

  Thus, in one embodiment, the optical sensor can initially be placed above the surface of the build region in the vicinity of the transition between the solidified and non-solidified regions of the build material. The build layer is generally oriented parallel to the xy plane so that the measured height corresponds to the z direction. The translation stage 208 can be controlled to move the lens 204 in the z direction until the value corresponding to the focus error is substantially zero. For this reason, it is known that at that position, the surface of the construction layer has a characteristic length in the z direction from the optical sensor. The optical sensor can then be translated laterally (eg, parallel to the xy plane) while maintaining its z-direction position. As the layer height changes, the surface moves closer to or away from the characteristic length, which results in a detectable change in the value corresponding to the focus error that can be recorded along with the xy position of the sensor. Will occur.

  If the change in height is sufficient for the distance between the sensor and the surface at a given position to approach the end of the linear operating range of focus error, operate the translation stage at that position. Thus, the sensor can be moved until the focus error reaches zero. Store the previously determined distance for that position and resume lateral scanning. In this way, it is possible to measure with high accuracy the overall height change of the transition region between the region of solidified building material and the region of non-solidified building material.

  As described above, the change in height across the transition region between the solidified and non-solidified regions of the build layer scans the optical sensor across the transition region, measures the change in the reflected beam profile, It is possible to process the measurement and obtain a change in height. As mentioned above, the optical sensor can be a sensor similar to an optical pickup for reading a CD / DVD, so that it can be easily obtained commercially with a small form factor and low cost. It is.

  Note that the optical sensor may include additional components in addition to those shown in FIG. For example, the optical sensor can include a quarter wave plate, an additional lens, and / or a diffraction grating. These components can be provided instead of or in addition to the components shown in FIG.

  In some embodiments, other types of sensors can be used to measure changes in height across the build layer. Other types of ranging sensors or distance measuring sensors can be used, such sensors may or may not be optical.

  The optical sensor can communicate with the controller 209. The controller 209 may include a processor that processes the signal detected by the optical sensor to determine a height value and thus an edge profile. The processor can be a dedicated processor for determining edge contours, or it can be a processor in an additive manufacturing system that also performs other tasks. However, in some embodiments, the readout circuit 206 can determine the height profile, in which case the controller 209 controls the settings of the additive manufacturing system based on the edge profile, as described below. It is possible.

  In some embodiments, the optical sensor can be mounted on a scanning stage that is movable relative to the build layer. A scanning stage 300 according to one embodiment is shown in FIG. The figure shows a construction layer 302 and a scanning stage 304 having an optical sensor 306.

  In some embodiments, the scanning stage can move relative to the build layer along a linear axis referred to herein as the scanning axis (eg, along the y-axis as shown by the large arrow in FIG. 3). . The scanning stage 304 can extend along an axis orthogonal to the scanning axis so as to cover the full width (eg, x-axis) of the build layer. The optical sensor 306 can move linearly along the scanning carriage (i.e., orthogonal to the scanning axis (e.g., along the x-axis as indicated by the small arrows in FIG. 3)). In this way, the light source can be moved in two dimensions to scan the entire area of the construction surface.

  It will be appreciated that other configurations of optical sensors are possible. For example, it is possible to move the optical sensor across the entire area of the building layer by separately moving a scanning stage that does not extend across the entire width of the building layer along two scanning axes. In a further example, the optical sensor can be constrained to move along a single axis, thereby restricting each scan to determine a profile along a single cross section of the building layer.

  The optical sensor can be mounted such that it can be placed at virtually any location within the scanning area of the build area. For example, if there is only one optical sensor, the scanning region can include the entire building layer. However, in some embodiments, there can be a plurality of optical sensors, in which one optical sensor of the plurality of optical sensors has a scanning region that does not extend throughout the building layer. It can be configured to have.

  The optical sensor can be placed on its own dedicated scanning stage. However, in some embodiments, the optical sensor can be placed on a scanning stage that also supports some other component of the additive manufacturing system. Any other component of the additive manufacturing system can be placed on the scanning stage, so that an optical sensor can be effectively added to the existing scanning stage. For example, the optical sensor may have a drug dispenser that dispenses a drug to a non-coagulated build material to control coalescence (eg, a drug dispenser for dispensing coalescing agents and / or coalescence modifiers). It can be placed on the stage. In some embodiments, the optical sensor can be placed on a scanning stage having a coating mechanism for coating the building surface with the next layer of building material. In some embodiments, the optical sensor can be placed on a scanning stage having a heating element for heating the build surface.

  In addition to the components described above, it will be appreciated that other components can be additionally or alternatively mounted on the scanning stage with optical sensors. Furthermore, the additive manufacturing system for producing a three-dimensional object can include two or more scanning stages.

  As mentioned above, the edge profile can be determined by measuring the change in the height of the building layer in the transition region between the solidified building material region and the non-solidified building material region. is there. The previous embodiment can be easily incorporated into an additive manufacturing system and used to determine the height change of the building layer after the building layer is formed and before the next building layer is formed. An optical sensor that can be described is described.

  Thus, the edge profile provides information regarding the quality of the edge of the slice of the object being formed. In some embodiments, the edge contour can provide an indication of the surface roughness of the finished object. A good quality edge can have a sharp transition between a region of solidified building material and a region of non-solidified building material. Such an edge can lead to an effective step-like height profile. The region of build material that has not solidified will have a first height and the region of solidified build material will have a lower second height. If there is a sharp transition between the two regions, there will be a stepped height change or height gradient over a relatively short lateral distance. However, in some cases, the edges may not be clear. It is possible that some (but not all) of the material outside the region corresponding to the slice of the object being created is solidified. Thus, a depth section through that portion of the building layer can encounter solidified and non-solidified building material. The resulting height of the building material at this point will be somewhere between the first height and the second height.

  An example of the contour is shown in FIG. FIG. 4A shows an example of the upper surface of the construction layer 401. The building layer 401 in this example includes a solidified building material region 402 and a non-solidified building material region 403. It will be appreciated that the number, shape, size, and location of the relevant regions will depend on the particular slice of the object or objects being created. The edge contour can be determined by measuring the change in height at least in the transition region between the region 402 and the region 403.

  FIG. 4A shows that a plurality of contours can be determined as indicated by broken lines AA ′ and BB ′, for example. FIG. 4 (b) shows that the height of the build layer (eg, measured in the z direction) can vary across the scan lines AA ′, BB ′ of the build layer. In the solidified building material region 402, the building material is coalesced and is therefore more compact than the non-solidified building material region 403. Accordingly, the height of the region of solidified building material 402 is lower than the region of non-solidified building material 403.

  FIG. 4 (c) shows an edge profile (eg, a circled edge profile between a solidified build material region 402 and a non-solidified build material region 403). As mentioned for a good quality edge, there should be a sharp or clean transition in the edge region, as shown by the lower reference contour in FIG. 4 (c). . The edge contour as shown in the upper example of FIG. 4C is an example of an edge contour that does not show a clear transition or a clean transition. It can be seen that the height of the edge profile varies over a relatively long lateral distance. It can also be seen that the steepest region of the edge contour is slightly offset from the staircase position in the reference contour. Thus, such edge contours can indicate that the edge of the solidified region of the build material is of relatively low quality.

  For this reason, the edge contour can be used to characterize the quality of the edge of the formed object. In some embodiments, the determined edge profile can be used to control the process settings of the additive manufacturing system. This can be done in a closed loop manner to improve the sharpness of the edge.

  FIG. 1b illustrates one embodiment of a method according to the present disclosure. Similar to the method described with reference to FIG. 1a, the method according to this embodiment may include forming a building layer (block 101) and determining an edge profile (block 102). is there. In this embodiment, the method can also include controlling process settings for forming the build layer (eg, controlling build parameters of the additive manufacturing system) (block 103) and then associated Proceed to forming a subsequent build layer using the processing settings (block 101).

  One embodiment of a method for creating a three-dimensional object using process setting control (eg, calibration of an additive manufacturing system) will be described with respect to FIG. The edge profile of the building layer can be determined by measuring the change in height across the transition between the region of solidified building material and the region of non-solidified building material (block 501). . The edge contour can be determined according to any of the embodiments described above.

  It can then be determined whether the edge contour characteristics are within tolerances of the reference characteristics (eg, of the reference contour) (block 502). This can include comparing the determined edge contour to a reference contour. The reference contour may have a shape such as a sharp edge contour as shown on the lower side of FIG. It will be appreciated that various reference contours are possible, including but not limited to step functions, flat slopes, or curves.

  Various characteristics are possible. For example, by analyzing the determined edge profile, a relatively constant height region corresponding to a fully solidified building material and a relatively constant height corresponding to a building material that is not fully solidified. It is possible to distinguish from another region. The distance between these two regions can indicate the width of the edge region, and the width of the edge region can be a characteristic. The characteristic can be the maximum and / or minimum slope of the height change in the edge region. The characteristic can be the position of the main change in height compared to the known position of the edge of the slice of the conceptual model of the object being created. The characteristic can be the presence of significant local maximums or minimums of bumps or height profiles in the edge region.

  In some embodiments, the edge contour is calculated by calculating the deviation of the contour measured at multiple points along the edge contour (eg, by subtracting the measured contour from the reference contour or each point Can be compared to a reference contour (by comparing the height at) with the reference contour (eg, a theoretical contour). In some embodiments, by comparing the deviation to a predetermined range of acceptable deviation values, the deviation can be used to determine whether the contour is within tolerance. If the measured deviation is greater than an acceptable value, the measured contour is not within the tolerance of the reference contour. If the measured deviation is less than an acceptable value, the measured contour is within the tolerance of the reference contour.

  If the determined edge contour is considered acceptable, for example, if the edge contour is within the tolerances of the reference contour and is sufficiently accurate for a particular construction, Indicates that it is working properly. Thus, it is possible to maintain the current settings of the additive manufacturing system (block 503). However, if the edge profile indicates that the edge is not acceptable, for example if the edge is not sharp enough for construction accuracy, adjust the processing settings (block 504) It is possible to try to improve. The processing setting can be adjusted by a controller such as the controller 209 shown in FIG.

  Accordingly, the process settings can be controlled based on the determined edge profile. The processing setting is a setting of the additive manufacturing system that can be controlled so as to change the characteristics of the processing layer to be processed (for example, the parameters for producing the three-dimensional object). If the determined edge profile is acceptable, the associated processing settings can be maintained. However, if the edge contour is not acceptable, the processing settings can be adjusted. In some embodiments, the processing settings can be adjusted as part of an edge enhancement routine that is performed in the course of forming several different building layers, as described in more detail below.

  Thus, in some embodiments, if the determined edge profile is not acceptable and a subsequent building layer (which need not be the next building layer) can be created (block 505), the processing settings are It is possible to adjust. It is therefore possible to determine the edge profile for this subsequent building layer. The edge contour can then be evaluated to determine whether the edge contour is currently acceptable. If the edge contour is currently acceptable, the current processing settings are maintained and no further adjustments may be required. However, if the edge profile remains unacceptable, the process settings can be adjusted again. This can be the same process setting or a different process setting. When adjusting the processing settings, it is possible to evaluate whether the quality has improved as a result of the previous change.

  Thus, the method can be repeated in an iterative fashion using an edge enhancement routine that changes processing settings (eg, construction parameters) between each layer until a contour that is within tolerances of the reference contour is determined. Is possible. At this point, the printed edge has acceptable sharpness and no further adjustment is necessary.

As mentioned in some embodiments, the process settings of the additive manufacturing system, i.e., the process settings of the fabrication process, can be controlled in an attempt to control edge sharpness. There are various factors that can affect the resulting edge sharpness of the building layer. Two such factors are listed below.
i) The amount of coalescence modifier used to limit or inhibit coalescence in the region adjacent to the region corresponding to the slice of the object being created. Increasing the amount of coalescence modifier applied to the edge region can reduce melting in the transition region.
ii) Temperature profile: The energy applied to the layer of building material (eg, the temperature of the fusing lamps) and the time that the layer of building material is exposed to an energy source such as a melting lamp is a function of the total amount of heat conduction. Influence. Increasing the lamp temperature and / or shortening the exposure time will make the edges clearer.

  Thus, the process setting that can be controlled can be the amount of coalescence modifier applied to the non-solidified build material to control coalescence. The amount of coalescence modifier can be controlled in various ways. Controlling the coalescence modifier drug dispenser to change the droplet size of the coalescence modifier supplied and / or dispensing the coalescence modifier drug to change the droplet density of the coalescence modifier. It is possible to control the vessel and / or to control the combination modifier drug dispenser to change the number of droplets of the combination modifier.

  The process setting that can be controlled is the alignment of the drug dispenser for dispensing the drug to the non-coagulated build material to control coalescence. For example, the alignment of the drug distributor for the coalescence modifier can be controlled, for example, by initiating calibration or adjusting the alignment.

  The process settings that can be controlled are the temperature settings that are applied to the layer of build material to form the build layer. The temperature setting can be the temperature of a heating means (for example, a fixing lamp). The temperature setting can be the time during which energy is applied to form the build layer.

  FIG. 6 illustrates one embodiment of a series of steps that can handle multiple treatment setting adjustments. Thus, FIG. 6 illustrates a series of processes that can follow an example of an edge enhancement routine. Such a plurality of steps can be performed by a controller such as the controller 209 shown in FIG. These multiple stages are incremental so that each stage can include a series of consecutive adjustments for different build layers (eg, to optimize a particular processing setting). Is possible.

  As mentioned above, one option to address insufficient edge definition is to increase the amount of coalescence modifier. Accordingly, the first stage of edge enhancement can include increasing or decreasing the amount of coalescence modifier supplied to the build material (block 601). In some embodiments, it may include increasing or decreasing the amount of coalescence supplied. In one embodiment, a series of iterations of the method of FIG. 5 can be performed to optimize edge sharpness, in which case the coalescence modifier or coalescence of each coalescence The quantity is modified according to the edge enhancement routine as shown in FIG. Thus, the edge enhancement routine can be implemented by a series of adjustments to the process settings.

  In some embodiments, the processing settings can be stored in a suitable memory along with an evaluation of the edge contours, or the edge contours of building layers formed using such settings. In this example, when the edge enhancement routine is executed, the edge contour obtained in the last iteration is compared with the edge contour obtained in the previous iteration. If the setting of the last iteration has improved over the previous iteration, it may be further changed towards the optimal value (ie the best value achievable to adjust that setting). Is possible. For example, if the edge sharpness is improved by increasing the amount of coalescence modifier, the edge enhancement routine will no longer affect the addition of coalescence modifier or begin to reduce the edge sharpness. Until then, it is possible to continue to gradually increase the amount of coalescence modifier. The optimal amount of coalescence modifier is found when the application of further coalescence modifiers has no effect or begins to reduce edge sharpness.

  After adjusting the amount of coalescence modifier and / or coalescence, if the output edge is still not within the tolerance of the reference contour, the edge enhancement routine may move to the next stage in some embodiments. Is possible. In the example of FIG. 6, the edge enhancement routine can then adjust the alignment of the drug dispenser. The lack of edge sharpness can be caused by the drug dispenser being offset and not delivering the associated drug to the correct area. Adjusting the alignment of the drug dispenser may include calibrating the alignment of the drug distributor (block 602). This can be done using an alignment routine (eg, a pen alignment routine) that can be part of a standard calibration process that is performed from time to time.

  This can also be performed over a number of iterations to find the optimal parameters (otherwise not detectable) and provide recognition of misalignment problems. As a result, the robustness and quality of the additive manufacturing system will be improved.

  In the example of FIG. 6, if the processed layer of processing material is still not within the tolerance of the reference contour after calibrating the alignment of the drug dispenser, the edge enhancement routine proceeds to the third stage of adjusting the temperature profile. To do. Changing the temperature profile can include increasing or decreasing the melting temperature, or extending or shortening the time interval during which the melting temperature is applied. This may include, for example, reducing the temperature of the energy source used during melting, or moving the energy source more quickly across the building surface to reduce the time that the building layer is exposed to the melting temperature. Is possible. This can also be carried out over a number of iterations of the method schematically illustrated in FIG. 5, whereby multiple layers of building material until the layer of building material falls within the tolerances of the reference contour. While forming the temperature profile, the edge enhancement routine changes the temperature profile. As described above, in some embodiments, the method can include storing the temperature setting in memory along with the resulting edge profile of the building layer formed with such a setting.

  In this embodiment, when the edge enhancement routine is executed, it is possible to compare the edge profile of the latest iteration with the edge profile of the previous iteration. If the temperature setting of the latest iteration provides an improvement over the previous iteration, then further corrections are made towards optimal values and / or until a building layer with an acceptable edge profile is generated It is possible. Once a layer having an edge profile that is within the tolerances of the reference profile is printed, no further adjustment is necessary.

  Therefore, this embodiment provides a calibration method for an additive manufacturing system. The calibration method can include determining an edge profile of a building layer formed by the system, the building layer comprising a region of solidified building material and a region of non-solidified building material. including. The edge profile can include a change in the height of the build layer across the transition between the solidified region of build material and the non-solidified region of build material. The method can include controlling system settings to achieve or maintain a predetermined edge profile.

  A calibration method (eg, a calibration method as described with respect to FIG. 5) can be performed only once during the build process (eg, at the beginning of the build process) to establish the appropriate settings, or The calibration method can be performed repeatedly at intervals or substantially continuously to ensure that sharp edge profiles are maintained throughout the construction process. For example, if the ambient conditions (eg, the average temperature of the construction area) change during operation, the method needs to be performed periodically. In some embodiments, the method can be applied at regular intervals during the building process (eg, every 100th layer of building material, or at other suitable intervals). In other embodiments, the method can be used at random intervals for quality control. It may be necessary to balance between performing the method periodically enough to ensure an accurate edge and not performing the method frequently enough to adversely affect build speed.

  By using the method of the above-described embodiment, an optimum edge profile can be achieved regardless of ambient conditions, ensuring that the build quality is not affected by changes in ambient temperature or humidity, for example. This improves the robustness and accuracy of the construction process and the quality of the finished object.

  Although the method, apparatus, and related aspects have been described with respect to particular embodiments, various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the present disclosure. Accordingly, it is intended that the method, apparatus, and related aspects be limited only by the scope of the claims and the equivalents thereof. The above embodiments are illustrative rather than limited to those described herein, and those skilled in the art will be able to design many alternative embodiments without departing from the scope of the claims. Note that it is possible.

  The term “comprising” does not exclude the presence of elements other than those listed in a claim, and the term “one” does not exclude a plurality; a single processor or other device may It is possible to implement a plurality of functions of a plurality of devices described in the section.

  The features of the dependent claims may be combined with any features of the independent claims or other dependent claims.

Claims (15)

A method of creating a three-dimensional object,
Forming a building layer comprising a region of solidified building material and a region of non-solidified building material, forming the building layer deposits a layer of non-solidified building material; and Processing to form a region of the solidified building material;
Determining an edge profile of the building layer, and determining the edge profile is a height of the building layer across a transition between the solidified building material region and the non-solidified building material region. Including measuring changes in depth,
A method for producing a three-dimensional object.   The method of claim 1, comprising controlling processing settings for forming a subsequent build layer based on the edge profile. Determine if the edge contour characteristic is within the tolerance of the reference characteristic and adjust the processing settings to form the subsequent building layer if the edge contour characteristic is not within the tolerance 3. A method according to claim 1 or claim 2 , comprising: . 4. The method of any one of claims 1 to 3, comprising controlling an amount of drug applied to the non-solidified build material to control coalescence of subsequent build layers based on the edge profile. The method according to item . Comprising the controlling based on the positioning of the distributor for dispensing a drug to the edge contour unclotted build material in order to control the coalescence of the subsequent building layer, claims 1 5. The method according to any one of 4 . 6. A method according to any one of the preceding claims , comprising controlling a temperature setting applied to form a subsequent build layer based on the edge profile. The change in height is measured using the optical sensor, the method according to any one of claims 1 to 6.   The method of claim 7, wherein the optical sensor is an optical focus error sensor. An additive manufacturing system,
Building layer preparation means for depositing a layer of non-solidified building material and processing the building material to form selected regions of solidified building material;
An additive manufacturing system comprising: a sensor that measures a change in the height of the layer over a transition between a region of solidified building material and a region of non-solidified building material.   The additive manufacturing system according to claim 9, further comprising a controller that controls a processing setting of the building layer manufacturing unit based on the measured change in height.   The additive manufacturing system according to claim 10, wherein the controller determines whether a characteristic of the edge contour is within a tolerance of a reference characteristic. 12. The additive manufacturing system according to claim 10, wherein the controller controls the amount of a medicine for controlling the coalescence provided by the building layer manufacturing unit based on the edge contour. Said controller, an alignment of the distributor of the construction layers produced means is controlled based on the edge contour, the distributor is intended to distribute the agent for controlling the coalescence claim 10 or claim Item 13. The additive manufacturing system according to any one of items 12 . The additive manufacturing system according to any one of claims 10 to 13, wherein the controller controls setting of a temperature applied by the construction layer manufacturing unit based on the edge contour. A method for calibrating an additive manufacturing system,
Determining an edge profile of a building layer formed by the additive manufacturing system, the building layer comprising a region of solidified building material and a region of non-solidified building material;
The edge profile comprises a change in the height of the building layer over a transition between the solidified building material region and the non-solidified building material region;
Controlling the settings of the additive manufacturing system to achieve or maintain a predetermined edge profile;
Calibration method for additive manufacturing system.

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